We adopt the social network perspective to develop a conceptual model and examine the relationship among human resource (HR) practices, interpersonal relations, and intrafirm knowledge transfer in knowledge-intensive firms. Our results indicate that work design, along with training and development HR practices, can shape the structural relation. At the same time, both also exhibit potential for shaping affective and cognitive relations within a firm's social network. While the effects of work design along with training and development HR practices on intrafirm knowledge transfer are primarily mediated by interpersonal relations, we found some evidence for arguing that incentives and motivation HR practices directly affect intrafirm knowledge transfer.